We plan to feed semipurified, cholesterol free diets to Vervet monkeys. These diets have been shown to cause hyperlipemia and aortic sudanophilia in this species. The diets will contain special fats which differ in their levels of oleic and elaidic acid. In addition to effects on serum and liver lipid levels, we will investigate the effect of these diets on serum and tissue fatty acid spectra and on activity of membrane-bound enzymes such as glucose-6-phosphatase and malate dehydrogenase. We will also feed monkeys a diet designed to approximate the composition of the "Western" diet and will examine the effects of added fiber on serum and liver lipids as well as on aortic sudanophilia. The two specific types of fiber which we will compare are cellulose and pectin.